Directional control valve



July 22, 1969 H. J. STACEY 5 DIRECTIONAL CONTROL VALVE Filed April 14.1966 INVENTOR HUGH J. STACEY BY m,m q.amuz&

ATTORNEYS United States Patent 3,456,671 DIRECTIONAL CONTROL VALVE HughJ. Stacey, Willoughby, Ohio, assignor to Parker- Hannifin Corporation,Cleveland, Ohio, a corporation of Ohio Filed Apr. 14, 1966, Ser. No.542,487 Int. Cl. GOSd 11/02, 11/16; F17d 3/02 US. Cl. 137-118 11 ClaimsABSTRACT OF THE DISCLOSURE A flow divider in which a valve element ismovable between first and second positions respectively closing andopening communication between an inlet passage and a first outletpassage, and an orifice plate movable relative to the valve elementbetween first and second positions respectively providing restricted andmore restricted communication between such inlet passage and a secondoutlet passage, such valve element and orifice plate being biased totheir first positions by a spring means which is effective uponpredetermined pressure drop across the orifice plate to yield to permitmovement of the valve element to its second position, and uponpredetermined greater pressure drop across the orifice plate, to yieldto permit movement of the orifice plate to its second position.

The present invention relates generally as indicated to a directionalcontrol valve and more particularly to a directional control valvehaving a priority flow divider in the inlet passage thereof.

In the case of fork lift trucks, front end loaders, back hoes, and thelike it is known to employ fluid motors for operating the lift forks,booms and buckets thereof and, in addition, provision is made for powersteering of such equipment. Generally, in the operation of suchequipment the power steering circuit, while mostly being used when thefluid motors aforesaid are not being actuated, must have fluid deliveredthereto to assure steering control at all times even though any or allof the fluid motors are being actuated. Of course, when the fluid supplyis more than adequate for the power steering control, it is desirablethat the surplus fluid be available for actuation of the fluid motors.

Accordingly, it is a principal object of this invention to provide aflow divider and priority valve to achieve the foregoing ends, that is,to make available for the priority circuit (e.g. the steering circuit) apredetermined minimum flow of fluid at all times and to make availableexcess fluid for operating the auxiliary circuit (e.g. the equipmentfluid motor circuit).

It is another object of this invention to provide a flow divider andpriority valve which is disposed in the path of inlet flow to adirectional control valve.

It is another object of this invention to provide a priority flowdivider which is operative to conduct a greater amount of fluid to thepriority circuit when the directional control valve or valves for theauxiliary fluid motor control circuit are in neutral position than whenthe latter are in an operating position thereby diverting a greateramount of fluid to the auxiliary control circuit at a time when lessfluid is required in the priority circuit.

Other objects and advantages of the present invention will becomeapparent as the following description proceeds.

To the accomplishment of the foregoing and related ends, the invention,then, comprises the features hereinafter fully described andparticularly pointed out in the claims, the following description andthe annexed drawing setting forth in detail a certain illustrativeembodiment of the invention, this being indicative, however, of but3,456,671 Patented July 22, 1969 one of the various ways in which theprinciple of the invention may be employed.

In said annexed drawing:

The single figure is a cross-section view of a directional control valvehaving a priority flow divider according to the present inventiondisposed in the pressure inlet passage, such section having been takenin a plane passing through the axis of the valve spool of thedirectional control valve.

Referring now to the drawing, the directional control valve V hereincomprises a housing 1 having a bore 2 in which the directional controlvalve spool 3 is axially reciprocable to control the operation of afluid motor (not shown). Said bore 2 is intersected axially therealongby (a) a bypass passage 4 which, at its upstream end, intersects anotherbore 5 in which the priority flow divider asembly 6 is disposed, andwhich at its downstream end, communicates with the return port 7 whichleads to a fluid reservoir; (b) a pair of pressure feed passages 8; 8which through the check valves 9; 9 communicate with the portion of thebypass passage which is between the bores 2 and 5; (c) a pair of motorpassages 10; 10 for connection with a fluid motor; and (d) a pair ofreturn pasages 11; 11 which also lead to the return port 7.

The housing 1 has a pressure inlet port and passage 12 which intersectsthe flow divider bore 5, and a priority circuit port and passage 14likewise intersecting the flow divider bore 5, between the inlet passage12 and one return passage 11 is a pressure relief valve 15 which openswhen the pressure in the inlet passage 12 exceeds a predetermined value.

By way of illustrative example, the spool 3 is of the four-way opencenter type for controlling a doubleacting fluid motor, not shown,adapted to be connected. with the motor pasages 10; 10. When said spool3 is in neutral position as shown, the bypass passage 4 is open from itsupstream end to its downstream end and both motor passages 10 areblocked from communication with the adjacent pressure feed and andreturn passages 8 and 11. When the spool 3 is moved downwardly from itsaforesaid neutral position, the bypass pasage 4 is closed thereby andthe upper pressure feed passage 8 is communicated with the upper motorpassage 10 for flow of fluid through the upper check valve 9 into oneend of a fluid motor, and the lower motor passage 10 is communicatedwith the lower return passage 11 for return flow of fluid from the otherend of the fluid motor. When the spool 3 is shifted upwardly from itsaforesaid neutral position, the lower pressure feed passage 8 iscommunicated with the lower motor passage 10 for flow of fluid throughthe lower check valve 9 into said other end of the fluid motor whilesaid one end of the fluid motor is open for return flow of fluid throughthe upper motor passage 10 which is in communication with the upperreturn passage 11.

Movable in the flow divider bore 5 is a tubular flow divider member 16which is biased by the spring 17 to a position shown wherein theopenings 18 in said member 16 are blocked by the portion of the bore 5between bypass passage 4 and inlet passage 12, thus to blockcommunication between the inlet passage 12 and the upstream end of thebypass passage 4.

Movable in said member 16 and biased by the spring 19 against the stopconstituted by the snap ring 20 in said member 16 is an orifice plate 21having a plurality of orifices 23 therethrough for flow of fluid throughthe tubular spring follower 24 and through the openings 25 in saidmember 16 which open into the priority passage 14.

The spring 19 has a higher preload than the spring 17 and, therefore,when the pressure drop across the orifice plate 21 exceeds the bias ofthe spring 17, the flow divider member 16 will commence to move upwardlyto progressively uncover the openings 18 to provide increas ing flow offluid from the inlet passage 12 to the up stream end of the bypasspassage 4 and if, at that time, the spool 3 is in neutral position, theexcess flow will be returned to a reservoir connected with the returnport 7. In the present example, the flow of fluid to the prioritycircuit via passage 14 may be 16 g.p.m. for example and any excess flowis diverted to the bypass passage 4 for return to a reservoir via returnport 7. Such upward movement of the flow divider member 16 will continueuntil the shoulder 26 thereof engages the spring follower washer 27 ofanother spring 28, at which time, the combined force of the springs 17and 28 is greater than the preload force of the orifice plate spring 19,whereupon continued increased pressure drop across: the orifice plate 21will cause the latter to move upwardly into engagement with the lowerend of the follower 24, thus to block all but the center one of theorifices 23.

Such movement of the orifice plate 21 will occur as when the spool 3 isshifted from neutral position to one of its operating positions, wherebypressure will build up in the upstream end of the bypass passage 4 andin the inlet passage 12, and such increased pressure will cause anincreased pressure drop across the orifice plate 21 effective to move itas aforesaid thus to restrict the flow of fluid to the priority circuitpassage 14 to a lower value and thus make available to the directionalcontrol valve a greater portion of the pump capacity. As an example, theflow capacity of the single orifice 23 may only be 4 g.p.m. which willbe adequate for power steering during operation of the lift or hoistcylinder of a fork lift truck, front end loader, etc.

At the time that the flow divider member 16 has moved up so that itsshoulder 26 engages the spring follower washer 27, the openings 18thereof provide for substantially full flow from the inlet passage 12 tothe upstream end of the bypass passage 4 and when the directionalcontrol valve spool 3 is in an operating position there will be a flowof 4 g.p.m. to the priority circuit passage 14 which is adequate forpower steering and the like at that time, while yet a major portion ofthe pump capacity will be available for equipment control circuitoperations.

In the event of still further increased pressure drop across the orificeplate 21 after it has engaged the follower 24, both springs 17 and 28will be compressed further by continued upward movement of flow dividermember 16. Such continued upward movement of member 16 begins toprogressively and successively close off the openings 25 as they enterthe bore 2 above priority circuit passage '14 thus to maintain thedesired minimum flow to the priority circuit passage 14 with increasedflow for fluid motor actuation.

Other modes of applying the principle of the invention may be employed,change being made as regards the details described, provided thefeatures stated in any of the following claims, or the equipalent ofsuch, be employed.

I therefore particularly point out and distinctly claim as my invention:

1. In combination, a directional control valve com prising a housinghaving a bypass passage with upstream and downstream ends for connectionwith a fluid pressure source and a reservoir respectively, a pressurefeed passage for connection with a fluid pressure source, a

motor passage for connection with a fluid motor, and a 1 valve memberbetween said motor passage and said pressure feed and return passages toat least one operating position whereat said bypass passage is closed bysaid valve member and whereat said motor passage is communicated withsaid pressure feed passage for fluid pressure actuation of such fluidmotor; said housing having a pressure inlet passage and another motorpassage; orifice means in said housing providing communication betweensaid inlet passage and said another motor passage; a priority flowdivider in said housing responsive to increasing pressure drop acrosssaid orifice means exceeding a predetermined value effective toprogressively open a. passage between said inlet passage and theupstream end of said bypass passage and said pressure feed passage; andmeans responsive to a predetermined greater pressure drop across saidorifice means to substantially decrease the flow capacity of saidorifice means whereby substantial fluid flow is available for fluidmotor actuation upon movement of said valve member to said one operatingposition, said priority flow divider comprising a valve element movablein a bore in said housing which is intersected by said inlet passage andanother motor passage, and first spring means biasing said valve elementto a position closing communication between said inlet and bypasspassages; and said orifice means comprising an orifice plate movable insaid valve element to decrease the flow capacity therethrough from saidinlet passage said another motor passage when moved from a firstposition ot a second position, and second spring means biasing saidorifice plate to said first position; said first spring means yieldingupon such predetermined pressure drop across said orifice plate topermit movement of said valve element to progressively opencommunication between said inlet and bypass passages, and said secondspring means yielding upon such predetermined greater pressure dropacross said orifice plate to permit movement of said orifice plate tosaid second position.

2. The combination of claim 1 wherein said valve element, upon yetfurther increase in pressure drop across said orifice plate, is movedagainst said first spring means to progressively decrease the flowcapacity of passages therein communicating with said another motorpassage.

3. The combination of claim 1 wherein third spring means bears on saidvalve element to yield together with said first spring means in responseto yet further increase in pressure drop across said orifice plate thusto permit movement of said valve element to progressively decrease theflow capacity of passages therein communicating with said another motorpassage.

4. The combination of claim 1 wherein said orifice plate has a pluralityof orifices therethrough; and wherein said valve element has a stoptherein engaged by said orifice plate in said second position to blockfluid fiow through at least one orifice.

5. A flow divider comprising a housing having a bore intersected by aninlet passage for connection with a fluid pressure source and by firstand second outlet passages for connection with fluid motors; a valveelement movable in said bore between first and second positionsrespectively closing and opening communication between said inletpassage and said first outlet passage; orifice plate means movablerelative to said valve element between first and second positionsrespectively providing restricted and more restricted communicationbetween said inlet passage and said second outlet passage; and springmeans biasing said valve element and said orifice plate means to theirrespective first positions and eifective, upon predetermined pressuredrop across said orifice plate means to yield to permit movement of saidvalve element to said second position and, upon predetermined greaterpressure drop across said orifice plate means to yield to permitmovement of said orifice plate means to said second position.

6. The flow divider of claim 5 wherein said spring means comprises firstand second springs respectively biasing said valve element and saidorifice plate means to said first position. v

7. The flow divider of claim 5 wherein said valve element is moved to athird position to restrict flow of fluid from said inlet passage to saidsecond outlet passage via said orifice plate means upon further increasein pressure drop across the latter when in said second position.

8. The flow divider of claim 5 wherein said spring means comprises firstand second springs respectively biasing said valve element and saidorifice plate means to said first positions; and wherein a third springbearing on said valve element yields to permit movement of said valveelement to a third position to restrict flow of fluid from said inletpassage to said second outlet passage via said orifice plate means uponfurther increase in pressure drop across the latter when in said secondposition.

9. The flow divider of claim 5 wherein said orifice plate means has aplurality of orifices therethrough; and wherein said valve element has astop therein engaged by said orifice plate means in said second positionto block fluid flow through at least one orifice.

10. The fiow divider of claim 8 wherein said valve element has ashoulder against which said third spring bears upon movement of saidvalve element to said second position, and means are provided formaintaining said third spring out of engagement with said shoulderduring movement of said valve element between said first and secondpositions, whereby only said first spring biases said valve elementduring such movements between said first and second positions.

11. In combination, a directional control valve comprising a housinghaving a bypass passage with upstream and downstream ends for connectionwith a fluid pressure source and a reservoir respectively, a pressurefeed passage for connection with a fluid pressure source, a motorpassage for connection with a fluid motor, and a return passage forconnection with a reservoir; a valve member movable in said housing froma neutral position whereat said bypass passage is open through saidvalve member and whereat communication is blocked by said valve mmeberbetween said motor passage and said pressure feed and return passages toat least one operating position whereat said bypass passage is closed bysaid valve memher and whereat said motor passage is communicated withsaid pressure feed passage for fluid pressure actuation of such fluidmotor; said housing having a pressure inlet passage and another motorpassage; orifice means in said housing providing communication betweensaid inlet passage and said another motor passage; a priority flowdivider in said housing responsive to increasing pressure drop acrosssaid orifice means exceeding a predetermined value effective to move toa position progressively opening a passage between said inlet passageand the upstream end of said bypass passage and said pressure feedpassage; and means responsive to a predetermined greater pressure dropacross said orifice means to move said orifice means relative to saidpriority flow divider to a position substantially decreasing the flowcapacity of said orifice means, whereby substantial fluid flow isavailable for fluid motor actuation upon movement of said valve memberto said one operating position.

References Cited UNITED STATES PATENTS 2,859,762 11/1958 Banker 1371083,160,167 12/1964 Martin 137596.12

WILLIAM F. ODEA, Primary Examiner H. M. COHN, Assistant Examiner US. Cl.X.R.

